There are a variety of devices which have mechanical arms or the like that function to manipulate tools and there is need for such devices to be able to interchange one tool for another during normal operation of the device. Robots are a prime example of such devices, see U.S. Pat. Nos. 4,281,447; 4,512,709; 4,549,846 and 4,652,203. Another example are manipulators carried by submarine vessels, see U.S. Pat. No. 4,227,853. The new devices of this invention have utility in all types of such tool exchange manipulators, but have special application for use with submarine vessel manipulators.
There are basically three types of tool interchange systems associated with submarine vessel manipulators. The first uses a small set of jaws to grasp the desired tool. The second uses a spindle indexer and the third uses a set of cones or frustums with locking elements, e.g., balls, to index the desired tool. The present invention provides the art with novel units of the third type.
Power to manipulator tools is delivered using two basic systems. In the case of the jaws-type tool holder, power to the tool is delivered in the form of hydraulic fluid through quick disconnects. In the case of spindle or cone type tool holders, the power is transmitted through a power take-off (PTO) centered in the device. Each type has advantages and disadvantages.
In the case where hydraulic disconnects are used, problems occur when the fittings are reconnected under water. Thus, small amounts of sea-water can be trapped in between the mating parts and can then be introduced into the hydraulic fluid supply. Alignment is also critical. On the positive side, hydraulics are highly versatile.
PTO's, in contrast to hydraulics, have less problems with alignment and are strictly mechanical, hence, do not affect the integrity of the hydraulic supply used for other power purposes in the overall system. On the con side, tools used with PTO's will generally need to be some type of compatible screw or rotary unit.
When using jaw-type tool indexers, several things become apparent. First, the jaws must be rotated so as to align them with the contact pads or grooves on the selected tool. Thus, X & Y alignment, rotation and angle of entry are critical in attachment of the tool to the jaw. Conversely, in the cone-type interchangers, there is a tendency to self-align the respective parts, given any play in the manipulator linkage. Axial alignment is of no importance since alignment of the cones can occur in any of 360.degree. and since the PTO is spring loaded to engage.
In the case of spindle-type tool exchangers, interchange requires precise X & Y alignment, as well as a critical entry angle. Axial alignment, again, is not critical since it can occur in any of 360.degree.. However, the attachment of the tool is not quite as rigid as the other two types since there must be clearance between the two mating parts. Power in the spindle-type interchangers is also transmitted to the tools using a PTO.
As there are three types of interchanger systems, there are also three types of systems used to maintain the tool in its respective holder. In the case of the jaw-type systems, hydraulic pressure must be maintained at all times to prevent the tool from disengaging.
In the case of the spindle-type holders, a pin is indexed into a groove in the spindle. Holes in the bottom of the groove also index the pin which keeps the tool from freely rotating in the holder.
The present invention avoids shortcomings of the jaws and spindle type holders by the use of a cone-type holder incorporating unique feature as disclosed hereinafter.